Antenna-in-packaging (AiP) enables the next generation of high-performance wireless 5G mmWave communication and beyond by incorporating antenna arrays in small form factors using System in Package (SiP) technology. The trend toward heterogeneous integration and advanced packaging will likely introduce more complexity to the semiconductor supply chain. In addition, there is also the risk of becoming more susceptible to security vulnerabilities associated with advanced packaging. This paper provides an overview of the supply chain vulnerabilities in advanced packaging and heterogeneous integration, followed by the existing security, reliability issues, and assurance of AiP. Apart from discussing existing physical modalities of AiP assurance and vulnerabilities, we propose Radio Frequency Fingerprint (RFF) as a new physical modality for AiP assurance. We also discuss possible future research direction and application of RFF in AiP assurance.